FIG. 3 shows a structure of a prior art semiconductor device having a light transparent window.
In FIG. 3, the reference numeral 1 designates a semiconductor chip in which light detectors such as two dimensional image sensors are highly integrated. The reference numeral 2 designates a light transparent window made of glass, the numeral 3 designates a wall produced of silicon rubber, for example, by a screen printing process. The reference numeral 4 designates a light receiving section having integrated light detectors. integrated. The reference numeral 5 designates a die bonding frame, the reference numeral 6 designates legs produced of lead frames, the reference numeral 7 designates a bonding pad of the semiconductor chip 1, the reference numeral 8 designates a wire made of a gold or copper metal alloy, and the reference numeral 9 designates molding resin.
A method for producing the semiconductor device will be described briefly with reference to FIG. 4 which shows an example of a method for producing the semiconductor device of FIG. 3.
At first, a wall 3 is produced of silicon rubber, for example, by a screen printing process on a wafer (refer to FIG. 4(a)). Usually, this wall 3 has a width of several 10 to several 100 .mu.m and a height of 5 to 50 .mu.m. Next, scribing is conducted for cutting out the chip 1, and the chip 1 is die bonded onto the lead frame 5 (refer to FIG. 4(b)) and (c)). Thereafter, wire bonding is conducted so that the window 2 adheres to the semiconductor chip 1 (refer to FIG. 4(d)) and (e)). Usually, glass which is optically polished and has a thickness of about 1 mm is used for the window material 2, and a lead frame is used of about 100 to 200 .mu.m thickness. Finally, a bending process of plastic molding is conducted to complete the legs of the semiconductor device (refer to FIG. 4(f)).
Herein, when an image sensor for a VTR camera is fabricated in the semiconductor chip 1, 200,000 to 400,000 light detectors having light detectors a square dimension of 10 .mu.m are integrated at the light detection section 4.
In the prior art semiconductor device having a light transparent window of such a construction, when flaws or dust are attached to the lower surface of the window (a surface close to the side of the chip), black flaws appear in the imaged screen. Because flaws or dusts make a shadow or cover a portion of the light receiving surface of the light detector due to the distance between the window material, the light detector is short as or equal to the distance determined by the thickness of the window material, that is, about several 10 .mu.m. Accordingly, even if the size of the flaws or dust is relatively as small as about 10 .mu.m, they appear as black flaws, and this lowers the yield of an image sensor eminently.